The present invention relates generally to communication systems, and more particularly to a method and apparatus for determining the status of a transmission link in a communication system.
Communication systems typically include multiple devices that communicate with each other over links connecting the devices. These links, commonly referred to as transmission links, are typically wirelines that run between ports on the devices.
Each device in a typical network knows the status of its ports. However, the device is typically not aware of the status of ports on other devices. Consequently, each device does not know the status of the link, since the status of the link is determined by the status of the two ports that the link is connected to. Therefore, each device is only aware of the status of its link, and through that status, whether the link attached to the port is operational.
Ports can have different statuses. For example, a port can be in-service, out-of-service, or testing. If a port is in an out-of-service state, for example, a transmission link utilizing that port typically cannot be used. However, the port at the other end of the transmission link is unaware of the status of the port on the other end, and in the view from that port, the transmission link is operational.
One approach used to test a transmission link between two devices is referred to as a loop-back test. In a loop-back process, a signal is sent over a transmission link from a first device to the second device. The message is immediately xe2x80x9clooped-backxe2x80x9d to the first device. In this manner, the transmission link can be tested to determine whether the transmission link is operational.
One problem with loop-back testing is that the transmission link is out of service while the loop-back testing is occurring. In addition, loop-back testing is typically a test condition, meaning that it is operator-driven. Typically, a loop-back test is performed after determining that there is a problem with the transmission link. The loop-back test is just one test used to determine the state of the link. Consequently, since the loop-back test is run only after an error has occurred, the loop-back test is not a real-time way of determining the status of the transmission link.
Therefore, a need exists for a method and apparatus that is able to determine in real-time the status of a transmission link between two devices.
It is an object of the present invention to provide a real-time solution to the aforementioned problem by utilizing the states of a first port and a second port to determine the status of a transmission link disposed between the first and second ports.
The present invention provides a method, apparatus, management device, and communication system for determining the status of a transmission link between a first port of a first device and a second port of a second device. The first device and the second device can be a switch, a phone, a computer, a modem pool, or any other piece of electronic equipment that is able to be coupled to another device.
The preferred embodiment of the present invention comprises receiving at the management device a first status of the first port and a second status of the second port. The first status is preferably determined at the first device and sent to the management device, while the second status of the second device is preferably determined at the second device and sent to the management device. The management device, which is preferably located remotely from the first device and the second device, receives the first status via a first path and the second status via a second path that is distinct from the first path. The first path and the second path can be distinct from the transmission link. The management device then calculates the status of the transmission link based on the first status and the second status.
In the preferred embodiment, the step of calculating the status of the transmission link comprises the step of setting the status of the transmission link to the greater, or most critical, of the first status and the second status. Accordingly, the status of the transmission link is calculated to be out-of-service if either the first status or the second status indicates that either link is out-of-service. An alarm can be sent when the status is calculated to be a predetermined value, such as an out-of-service alarm. In addition, a log can be updated when the status is calculated to be a predetermined value.